2 cups milk (any fat %), warmed to not quite boiling
1 tsp dried thyme
1 tsp dried oregano
1 cup grated cheddar cheese
1 cup grated Gruyere
salt and freshly-ground black pepper
1.5 lbs. potatoes (I used Russet) very thinly sliced
1 lb boneless, skinless chicken breasts, cubed
1½ cups fresh green beans, cut to 1" segments
1 lemon, halved and thinly sliced
Instructions
Preheat the oven to 425 F.
In a large saucepan over medium heat, melt the butter. Add the garlic and onion, and cook until softened — 3-5 minutes.
Whisking constantly, add the flour. Continue to whisk and cook the roux for 3 minutes before adding the hot milk, thyme, and oregano. Whisk and cook until the mixture comes to a boil and thickens. Cook for another two minutes, then add the cheese, whisk until fully melted, and remove from heat. Add salt and pepper to taste.
In a large bowl, combine the potatoes, chicken cubes, green beans, and cheese sauce. Mix well to fully coat everything in the sauce, then pour into a large casserole pan (I used a 9x13 baking dish, but could have gone bigger!).
Tuck the lemon sliced in along the top, cover with foil, and bake for 50-60 minutes, or until your potatoes are tender. Remove the foil, and broil until the top of the casserole is golden.
Remove from the oven, and serve warm.
Notes
If you are making this gluten-free, be sure to use a gluten-free thickener in place of the flour. I've found Bob's Red Mill All-Purpose GF Flour to work perfectly as a thickener when making a roux.
Recipe by The Kitchen Paper at http://c02.ddd.mwp.accessdomain.com/lemon-chicken-potato-casserole/